My cruise control doesn’t work when the lights are on?

This sounds like the brake light switch is shorted out or having problems, here is the location so you can replace it. IF the switch is okay, we need to run the codes because it could be a bad MICU, you can get a CAN scanner (Controller Area Network) which will work on most cars from Amazon.

here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Check out the images (below). Please let us know what happens.